Today, there are growing expectations for stable supply of power. In addition, distributed power supplies such as photovoltaic power generation and wind power generation as well as storage batteries are gaining popularity. Furthermore, it appears more likely that so-called separation of power generation from power transmission and distribution in which different business operators respectively perform power transmission and power distribution is to be implemented.
Accordingly, there are signs of a beginning of a change from a conventional configuration where power is supplied from a large-scale power plant to equipment of end consumers by a treelike power transmission and distribution grid to a locally-produced and locally-consumed power supply-demand system where power is respectively generated in each area and the generated power is consumed in that area.
A technique using a multi-terminal asynchronous linking apparatus (refer to PTL 1) is proposed as means for constructing a locally-produced and locally-consumed supply-demand system. The conventional technique involves forming small power transmission grids using coupling apparatuses capable of converting alternating current into direct current and converting direct current into alternating current and transferring power among the small power transmission grids.